JPS6124010B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a respiratory and cardiac motion measuring device for measuring the state of respiratory motion and cardiac motion of a living body to be examined.

``Prior art'' In order to get an idea of the health condition of a living body under test, the number and amount of respiration of the living body under test, that is, the amount of air ventilation in the lungs, is measured, and the heart rate, so-called pulse rate, is measured. is being measured.

These are not only measured as parameters of the health status of the subject, but also the breathing rate and heart rate of a subject who has undergone major surgery can be measured to determine if the subject is still alive. 2. To monitor whether the patient is alive or in critical condition.
Measurements are carried out for three consecutive days, and respiration and heart motion are similarly measured all the time for immature test organisms.

By the way, in the conventional measurement of breathing and heart motion, a thermosensor, such as a thermistor, is attached to the entrance of the nostril, and the electrical resistance of the thermosensor changes with the flow of air generated in response to breathing. A method is used in which the number of respirations is detected by electrically detecting the number of respirations. Alternatively, a conductive rubber band is attached to the chest, and the number of breaths is measured by using the change in resistance of the rubber band as it expands and contracts due to chest movement associated with breathing. There are methods that measure the number of breaths by attaching a converter near the mouth that converts the flow of air into and out of the mouth into electrical signals, and methods that measure the number of breaths by attaching electrodes on both sides of the lungs and measuring the impedance between the electrodes. A method of measuring .

Regarding the movement of the heart, the heart rate was measured using a so-called electrocardiogram.

``Problems to be Solved by the Invention'' As described above, in all conventional devices, some kind of object such as a detector or a converter is attached to the living body under test, and a lead wire is connected to the attached object. Ta. Attaching such objects and lead wires to a living body that has undergone surgery, for example, is a nuisance for the living body, and leaving them attached for two or three days is a nuisance to the living body. This is not desirable in terms of the health of the specimen. For example, a so-called rash may occur on the skin of the subject at the contact portion of the electrode or the like.

In addition, these objects such as detectors and transducers attached to the living body to be tested and lead wires for these objects are a nuisance not only to the living body to be tested but also to the person performing the measurement operation.

Furthermore, when measurements are performed by attaching objects such as detectors and transducers and lead wires thereto to the living body to be examined, measurement results that differ from those in normal times may be obtained. In other words, the installation of objects such as detectors and transducers and lead wires to them may have a different mental impact on the living body than in normal conditions, and may cause measurements to be taken that are different from normal breathing and pulse measurements. There may be consequences.

This invention was made in view of the current state of conventional respiratory and cardiac motion measuring devices of this type, and its purpose is to do so in a non-contact state with respect to the living body, that is, to remove objects such as detectors and transducers and leads. The present invention provides a respiratory and cardiac motion measuring device capable of measuring respiratory motion and cardiac motion without attaching wires or the like.

"Structure of the Invention" According to the present invention, a measuring table is provided on which a living body to be examined is placed in a substantially horizontal state, and the position of the center of gravity of the living body changes in response to fluctuations in the center of gravity caused by cardiac and respiratory movements of the living body to be examined. A load detector for detecting the load value of the living body is provided at the periphery of the measuring table.

In this invention, based on the distance from the reference position of the measuring table to the load detector, the load value detected by the load detector, and the body weight of the subject, a calculator calculates the center of gravity of the subject by balancing moments. A positional variation output is calculated.

On the other hand, the respiration and cardiac motion measuring device of the present invention is provided with a filter, and this filter allows the cardiac motion of the subject to be detected from the high frequency component of the fluctuation output of the center of gravity position of the subject, which is obtained by the arithmetic unit. is detected. Furthermore, this filter detects the respiratory motion of the subject living body from the low frequency component of the fluctuation output of the center of gravity position of the subject body obtained by the computing unit.

In this way, according to the respiratory and cardiac motion measuring device of the present invention, it is possible to measure the respiratory motion and cardiac motion of the living body under test in a non-contact state, thereby causing no inconvenience to the living body under test. It does not make the patient feel any sensation, and does not harm the health of the living body due to the attachment of the detector, transducer, lead wire, etc.

Furthermore, the person who operates the respiratory and cardiac motion measuring device can also smoothly perform measurements without feeling bothered by the non-contact measurement.

In addition, since the measurement is performed in a non-contact state, it is extremely unlikely to have any psychological impact on the subject during the measurement, which is different from the normal state of breathing and cardiac movements of the subject. Highly accurate measurement becomes possible.

``Example'' The respiration and cardiac motion measuring device of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the configuration of an embodiment of the present invention. For example, a plate-shaped measuring table 11 is arranged horizontally so as to be able to rotate about one end 12 as a fulcrum, and the other end is supported by a spring as a load detector. It is held at 13. The living body 14 to be examined is placed horizontally, for example, on its back, on the measuring table 11.

A load value of the living body to be tested 14 that changes in response to a change in the center of gravity position of the living body to be tested 14 caused by cardiac motion and respiratory motion of the living body to be tested is detected by a load detector.

The distance from the center of gravity 15 of the living body 14 to the fulcrum 12, which is the reference position of the measuring table 11, is x, and the living body 14 to be tested is
Let P be the weight of , a moment x acts around the fulcrum 12 . On the other hand, the fulcrum 12 is the reference position
Assuming that the distance from the spring 13 to the spring 13 is F, and the force that the spring 13 receives is F, a moment F acts on the fulcrum 12.

In this invention, the spring 1, which is a load converter, is
From the distance to 3, the load value F detected by the load converter, and the weight P of the living body 14, a fluctuation output of the center of gravity position of the living body 14 is calculated by balancing the moments.

That is, from the balance of the moment with respect to the fulcrum 12, x·P=·F is obtained, and the distance x from the fulcrum 12 to the center of gravity 15 of the living body 14 to be examined is obtained by the following equation.

x=/P・F...(1) From equation (1), since the weight P and distance are constant, the center of gravity of the living body 14 can be determined by measuring the force F applied to the spring 13, which is a load converter. A position x is measured. The distance x from the fulcrum 12, which is the reference position, to the center of gravity 15 of the living body 14 changes slightly due to the cardiac motion and respiratory motion of the living body 14 to be tested.
Due to this change in distance x, the load value F detected by the spring 13, which is a load detector, expressed by equation (1) changes. Therefore, by detecting the load value F by the spring 13, the calculating unit calculates the fluctuation output x of the center of gravity position of the living body 14 based on equation (1).

FIG. 2 shows an arithmetic unit in an embodiment of the present invention, and in the embodiment, the arithmetic unit is composed of a load converter 16 and an amplifier 17. The force F detected by the spring 13, which is a load detector, is transmitted to the load converter 16.
The output is converted into an electrical signal by an amplifier 17.
The signal is amplified at , and an operation based on equation (1) is performed.

A filter is provided that detects the cardiac motion of the living body 14 from the high frequency component of the fluctuating output obtained by the arithmetic unit, and detects the respiratory motion of the living body 14 from the low frequency component of the fluctuating output.

That is, as shown in FIG. 2, a low-pass filter 18 and a high-pass filter 19 are connected in parallel to the output terminal of the amplifier 17.

The low frequency components in the output of the amplifier 17 of the arithmetic unit are extracted through a low pass filter 18, and the high frequency components are extracted through a high pass filter 19. A recorder 21 is connected to the output terminal of the amplifier 17 in parallel with the filter, and the recorder 21 records the output signal of the amplifier 17 on recording paper. The output signal of the amplifier 17 recorded by the recorder 21 is as shown in FIG. 3A, for example.

Amplifier 1 recorded on the recording paper of this recorder 21
Looking at the waveform of the output signal of No. 7, the waveform of the output signal has a pulse-like high frequency component 2 with respect to a low frequency component 22.
It can be seen that 3 are superimposed. Low frequency component 22
indicates a change in the center of gravity position corresponding to the respiration of the living body 14 to be examined. This occurs because the thorax of the living body 14 expands every time the living body 14 breathes, which causes the position of the center of gravity 15 of the living body 14 to change, and this variation occurs particularly in the body length direction of the living body 14. big. As a result of experiments by the inventors, the output signal of the amplifier 17 was recorded on the recorder 21, and at the same time, respiration was measured and recorded using a conventional respiration measuring means, and the two were compared. It was confirmed that the waveform of the low frequency component 22 corresponds to the waveform of the low frequency component 22, and it was confirmed that the low frequency component 22 in FIG. 3 corresponds to respiratory motion.

The inventors also measured an electrocardiogram at the same time as this measurement, and compared the electrocardiogram with the high frequency component 23 in Figure 3A.
It was confirmed that the high-frequency pulse 23 corresponds well to the waveform of the heartbeat, indicating that the high-frequency pulse 23 corresponds to the heartbeat. That is, since the heart moves with each heartbeat of the living body 14 to be tested, the center of gravity of the living body to be tested moves, and this appears as a high frequency component 23.

Therefore, when the low-frequency component 22 is extracted by the low-pass filter 18 in the filter, the respiratory movement of the living body 14 to be examined is detected, and the high-pass filter 19 in the filter
When the higher frequency component 23 is extracted, the heart motion of the subject is detected. The recorded waveform of the output of the low-pass filter 18 is shown in FIG.
The recorded waveform of the output is shown in FIG. 5A. In these cases, the cut-off frequency of both the low-pass filter 18 and the high-pass filter 19 is 2 hertz, and the moving speed of the recording paper is 12.5 mm/sec.

To count the respiration rate, the output signal of the low-pass filter 18 is passed through a shaping circuit 24 as shown in FIG.
The respiration rate can be measured by shaping the waveform into a square wave and counting the square wave using the counting circuit 25. Also, the output of the high-pass filter 19 is converted into a square wave by the waveform shaping circuit 26, and the output is converted into a square wave by the counting circuit 2.
By counting at step 7, the heart rate of the subject 14 can be measured. Or low pass filter 1
The outputs of 8 and high-pass filter 19 are respectively supplied to an autocorrelator, and the frequencies of low frequency component 22 and high frequency component 2 are determined as frequencies with large autocorrelation.
It is also possible to measure each of the three frequencies.

Alternatively, by supplying the output signal of the amplifier 17 to what is called a periodogram, it is possible to detect the autocorrelation of each of the low frequency components and high frequency components and measure these frequencies. The present invention not only measures in this way, but also measures the living body 14 by looking at the recorded waveforms obtained as shown in FIGS. 3, 4, and 5 and counting their peak values. It is also possible to know the breathing rate and heart rate.

Furthermore, each level of the low frequency component 22 or the high frequency component 23 is measured, and the magnitude of the low frequency component 22 is measured as corresponding to the respiration volume of the subject, that is, the ventilation volume in the lungs. Similarly, it is assumed that the peak level of the high frequency component 23 corresponds to the cardiac output of the subject, and by measuring this peak level, the cardiac output of the subject can be measured.

These measurements are carried out by a low pass filter 18, respectively.
Each output of the high-pass filter 19 may be measured using a level meter, or it may be possible to record the output on a recording paper of the recorder 21 and read the amplitude from the scale of the waveform.

By the way, as mentioned above, the movement of the center of gravity of the living body under test is based on the movement of breathing and the heart, and these movements also cause the center of gravity of the living body to move in the vertical direction. Weight fluctuates due to movement. Therefore, for accurate measurement, it is necessary to compensate for the effects of weight fluctuations.

From this point of view, for example, as shown in FIG. 7 and FIG.
1 at its four corners, respectively, load converters 31
It is also possible to adopt a configuration in which the information is received at 34 to 34. In this other embodiment, a load converter is used as the load detector, and a load signal directly converted into an electrical signal is obtained from the load converter.

Each load received by these equal load converters 31 to 34 is
P ₁ to _{P 4} , between load converters 31 and 34 and heavy converter 3
Let m be the respective distances between the load converters 2 and 33, and let be the distances between the load converters 31 and 32 and between the load converters 34 and 33. Further, the height direction of the living body 14, that is, the arrangement direction of the load transducers 31 and 32 is taken as the X axis, and the direction in the horizontal plane perpendicular to this, that is, the arrangement direction of the load transducers 31 and 34 is taken as the Y axis, and the center of gravity 1
Assuming that the X component at position 5 is x and the Y component is y, the following equation can be obtained from moment balance.

P*x=(P ₂ +P ₃ )...(2) P*y=(P ₃ +P ₄ )m...(3) From these equations (2) and (3), the following equation is obtained.

x=P ₂ +P ₃ /P·...(4) y=P ₃ +P ₄ /P·m...(5) Furthermore, the formula holds true between P ₁ to _{P 4} and P.

P=P ₁ +P ₂ +P ₃ +P ₄ ...(6) Also, by integrating twice the load in the vertical direction, that is, the Z-axis direction, that is, the change △P in the body weight P of the subject 14, the center of gravity in the Z direction can be calculated. The position of 15 is found.

In other embodiments, adder circuits 35 to 37, divider circuits 38 and 39, and Z
The detection circuit 41 constitutes an arithmetic unit.

The respective output signals of the load converters 31 to 34 are added together in an adding circuit 35, that is, the body weight P is obtained. Further, the output signals of the load converters 32 and 33 are added in an adder circuit 36 to obtain P ₂ +P ₃ , and the output signals of the load converters 33 and 34 are added in an adder 37 to obtain P ₃ +P ₄ is obtained.

P ₂ +P ₃ /P is calculated in the division circuit 38 and the center of gravity 1
The x-coordinate of the position of the center of gravity 15 is determined, and the division circuit 39 calculates P ₂ +P ₄ /P to obtain the y-coordinate of the center of gravity 15. Further, the variation in the output P of the adder circuit 35 is integrated twice by the Z detection circuit 41 to obtain Z.

When the output of the divider circuit 38 thus obtained was recorded, a waveform completely similar to that recorded in FIG. 3A was obtained. The record of the output of the divider circuit 39 is shown in Fig. 3B, and there is almost no change, and the record of the output of the Z detection circuit 41 is shown in Fig. 3C, which is similar to Fig. 3A. It is confirmed.

Therefore, the output of the dividing circuit 38 is a desirable output, and by recording this output and separating it into low frequency components and high frequency components using a filter, the respiratory rate, heart rate, and respiratory rate of the living body 14 can be determined. (ventilation volume) and cardiac output can be obtained.

According to the respiration and cardiac motion measuring device according to the present invention, the respiration and cardiac motion of the subject 14 can be measured without attaching any object such as a detector or converter or lead wire to the subject. I can do things. For example, when applying this invention to the human body,
The patient's bed may be used as the measurement table 11, or a slightly slanted chair-like object such as an easy chair may be used. In any case, for this measurement, there is no need to attach lead wires to objects such as detectors and transducers to the living body under test, and therefore accurate measurements can be obtained without being affected mentally by attaching objects. Moreover, there is no need to attach objects to subjects undergoing surgery or premature infants, thereby causing them to feel troublesome.

Therefore, it is possible to perform measurements while the living body under test is in a resting state, and even if the measurement is carried out for a long time, the living body will not be affected in any way. Furthermore, since no objects or lead wires are attached to the living body to be examined, there is no possibility that the living body to be tested will get a rash due to the electrodes, and furthermore, since the lead wires are not connected to the living body to be examined, handling is convenient. Furthermore, it is possible to measure not only the respiratory rate and heart rate but also the respiratory volume and cardiac output of the living body under test.

In the above-mentioned embodiments, measurements were taken with the subject body facing up, but measurements may also be taken with the subject body lying on its stomach or lying on its side. Although the case where both cardiac motion and respiratory motion are measured has been described, only one of them may be measurable. For example, if it is necessary to measure an electrocardiogram at the same time, only respiratory motion may be measured. In addition, in the other embodiments shown in FIGS. 7 and 8, highly accurate measurements can be obtained as described above, and in particular cardiac output can be measured, which was previously impossible to obtain. It becomes possible to measure stroke volume with high precision. In addition, according to the other embodiments shown in FIGS. 7 and 8, it is also possible to detect changes in the body weight of the subject; for example, when a dehydrated patient is the subject, It is also possible to monitor weight changes at the same time as measuring respiratory and cardiac movements. Further, with the respiration and cardiac motion measuring device of the present invention, it is possible to measure, for example, the number of times a patient turns over in bed, the number of times an asthmatic patient coughs, etc. based on changes in the position of the center of gravity. Furthermore, in the respiratory and cardiac motion measuring device of the present invention, it is also possible to attach an alarm device to detect when the respiratory motion or cardiac motion of the subject is in a dangerous state.

``Effects of the Invention'' As explained in detail above, according to the present invention, cardiac movement can be performed in a non-contact manner without attaching objects such as detectors or lead wires to the living body being examined, and without causing any nuisance to the living body being examined. It is possible to measure and detect respiratory movements with high precision.

Since it is possible to measure the subject's mental state in the same way as normal, the data on heart motion and respiratory motion obtained is extremely reliable. Since there is no need to attach any other equipment, measurement operations can be carried out extremely smoothly.

[Brief explanation of the drawing]

FIG. 1 is a side view showing the configuration of an embodiment of the respiration and cardiac motion measuring device of the present invention, FIG. 2 is an electrical block diagram showing the configuration of the embodiment of the invention, and FIGS. 3 to 5 are: Recorded waveform diagrams obtained by measuring with each respiration and cardiac motion measuring device of this invention,
FIG. 6 is a diagram showing an example of a specific processing circuit for output signals of the respiration and cardiac motion measuring device of the present invention, and FIG. 7 is a plan view showing the configuration of another embodiment of the respiration and cardiac motion measuring device of the present invention. 8 is a side view of FIG. 7, and FIG. 9 is a circuit diagram showing the configuration of a load detector, an arithmetic unit, and a filter in another embodiment shown in FIGS. 7 and 8.

Claims (1)

[Scope of Claims] 1. A measuring table on which a living body to be examined is placed in a substantially horizontal state, and a measuring table provided at the periphery of this measuring stand to measure the amount of the living body to be examined caused by cardiac motion and respiratory motion of the living body to be examined. a load detector that detects a load value of the living body under test that changes in response to a change in the center of gravity; a distance from a reference position of the measurement stand to the load detector; a load value detected by the load detector; a computing unit that calculates a variation output of the center of gravity position of the subject living body based on the weight of the subject living body by moment balance; 1. A respiratory and cardiac motion measuring device, comprising: a filter that detects cardiac motion and detects respiratory motion of the living body from low frequency components of the fluctuating output.